Is there anybody who was had something like this? I can't really think that so much noise comes from a ISO from 640?

Maybe my censor from the camera became to hot (i read online that this can also cause noise)

And there is a good change that my camera was to hot cause it was sitting exactly under the main lamp (800watt) which lights the front of the character. Today i am going to make the same shot with a cold camera and see if that was the problem.

Meanwhile i hope somebody on the forum can lead me in the right direction to solve the problem.